Ceftaroline fosamil ((6R,7R)-7-[(2Z)-2-ethoxyimino-2-[5-(phosphonoamino)-1,2,4-thiadiazol-3-yl]acetyl]amino]-3-[4-(1-methylpyridin-1-ium-4-yl)-1,3-thiazol-2-yl]sulfanyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate; Teflaro) is a cephalosporin antibiotic which is active against methicillin-resistant Staphylococcus aureus and Gram-positive bacteria. It has the general formula
whereby the compound is generally provided in the form of its acetic acid solvate.
EP-A-1 043 327 discusses certain phosphonocephem derivatives:

Salts of these compounds are also disclosed.
EP-A-1 310 502 discloses a process for preparing ceftaroline fosamil which includes the following reaction step.

Scavengers such as certain alkali metal salts, tertiary amines, and alkylene oxides can be present in this step.
It was an object of the present invention to provide an improved process for producing ceftaroline fosamil which requires less reaction steps. It was a further object of the present invention to provide an improved process for producing ceftaroline fosamil which results in a lower formation of by-products.